Mineral oil compositions resistant to foaming



Patented Nov. 2, 194a MINERAL on.

COMPOSITIONS RESISTANT TO FOAMIN G Herschel G. Smith, Wallingford, andTroy L. Cantrell, Lansdowne, Pa., assignors to Gulf Oil Corporation,Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. ApplicationOctober 4, 1946, Serial No. 701,072

This invention relates to improvedmineral oil compositions resistant tofoaming.

In lubricating machinery and other devices with oils, in handling oilsas by pumping, in handling oil under reduced pressures and intransmitting power with an oil medium, conditions are often such thatthe oil is subjected to violent agitation in the presence of air orother gases, thus-tending to produce foam or froth. In most casesfoaming or frothing is quite objectionable. For example, in thelubrication of gears the foaming produced by the churning action of thegears on the lubricant gives rise to excessive leakage, improperlubricatiomand loss of lubricant past retainer rings, etc. Gears such asthose used in transmission and differential gear assemblies oftenoperate at very high speeds, as well as under hightooth pressures, andtherefore they require a I very good lubricant to prevent or retardexcessive wear due to surface-to-surface contact.

The lubricants employed usually are viscousoils, often containing aso-called extreme pressure agent to assist in maintaining an 011 filmbetween the teeth. If the lubricant contains air dispersed through it,it' lacks proper'fllm forming properties. In reduction gears,particularly herringbone gears oil aerofoam is undesirable as it tendsto produce pitting or corrosion at the point of maximum pressure.Moreover, foaming oil is usually much less effective in conductingviolent agitation. The more viscous the oil, the

greater the amount of foam, and the longer it persists after agitationis stopped.

In pumping oils with rotary gears, displacement, or other type pumps,foam or gas pockets often interfere with the pumping of the oil, causinga reduction in the stream of oil flow. This condition may be caused byeither the vacuum on the intake or by the entrainment of 'gas due toviolent agitation. In placing oil under vacuum, it sometimes is foundthat the foaming characteristic of the oil is such as to cause loss ofoil entrained in the gas removed. This loss of oil is objectionable. Forexample, as'an airplane climbs to high altitudes, the temperature 8Claims. (Cl. 252-325) and pressure of the oil in the sump and oil linesmay be decreased, conditions which promote foaming tendencies which arehighly undesirable.

It is an object of our invention to provide mineral oil compositionsresistant to foaming.

It is a further object of our invention to provide a mineral oilcomposition having a decreased tendency to foam or froth under severeconditions.

In our copending application Serial No. 582,402, filed March 12, 1945,now U. S. Patent No, 2,411,671, there is disclosed and claimed mineraloil compositions containing a class of compounds which function in anexcellent manner to reduce the foaming tendency of mineral oils. Thesewherein R represents an alkyl group containing 1 to 18 carbon atoms, Yis a substituent of the class consisting of monovalent metals and alkylgroups, X represents a substituent of the class consisting of metals andan organic ammonium group derived from the class consisting ofheterocyclie nitrogen bases and dialkylarylamines, m is a numbercorresponding to the valence of X, and n' is from 2 to 6. Representativeof this class of compounds are potassium trioctyl ethylene diphosphate,dimethylaniline trioctyl ethylene diphosphate, potassium dimethylanilinedioctyl ethylene diphosphate and disodium dioctyl isobutylenediphosphate. As shown in our copending application, these compounds areprepared by reactingan alkylene glycol having from 2 to 6 carbon atomsand a saturated aliphatic monohydric alcohol having from 1 to 18 carbonatoms with phosphorus oxy-chloride or phosphorus pentoxide, andneutralizing the residual acidity with a base to yield a metal ororganic ammonium salt of the alkyl alkylene diphosphate. As may be seenfrom the examples of our copending application, generally, the mol ratioof the alkylene glycol to the phosphorus compound is 1:2 in the case ofphosphorus oxychloride and 1:1 in the case of phosphorus pentoxide. Inother words, the molar equivalent of the phosphorus compound on thebasis of available phosphorus yields a ratio of mols of alkylene glycolto molar equivalents of phosphorus compound of 1:2.

We have now discovered another class of compounds which are excellentinhibitors in mineral oil compositions for reducing the foaming.tendency of mineral oils. In accordance therewith, the objects of ourinvention are accomplished by providing a mineral oil compositioncomprising a mineral oil and a minor amount, at least suflicient toreduce the foaming tendency of the mineral oil, of a salt of (1) asalt-forming constituent selected from the class consisting of metalsand an organic ammonium group derived from the class consisting ofheterocyclic nitrogen bases and N-dialkylarylamines and (2) the viscousliquid reaction product of 1 mol of a glycol having from 2 to 6 carbonatoms, 1 molecular equivalent of a phosphorus compound selected from theclass consisting of phosphorus oxychloride and phosphorus pentoxide and1 mol of a saturated aliphatic monohydric alcohol having from 1 to 18carbon atoms.

More particularly, we have found that when the number of mols of theglycol and the number of molar equivalents of the phosphorus compoundare in the ratio of 1:1, the alkylene diphosphates described in ourcopending application are not obtained, but there is obtained instead aviscous liquid material of unknown constitution, which we believe to bepolymeric in nature. By the term molar equivalent" or "molecularequivalent as used herein and in the appended claims, we mean the numberof equivalents of phosphorus compound (based on the availablephosphorus) which .combine with the glycol in accordance with ourinvention. Thus, both phosphorus pentoxide and phosphorus oxychloridehave molar equivalents of one, even though phosphorus pentoxide containstwo atoms of phosphorus. In other words, when phosphorus oxychloride isreacted with the glycol, one mol of each compound is used; whereas whenphosphorus pentoxide is reacted with the glycol. there being two atomsof phosphorus in the phosphorus compound, one mol of glycol will be usedfor each half mol of phosphorus pentoxide.

In producing our new class of compounds, any of the alkylene glycolscontaining from 2 to 6 carbon atoms, as shown in our above-identifiedco-' pending application may be employed. Thus, we may use ethyleneglycol, the propylene glycols, the butylene glycols, amylene glycol andhexylene glycol or mixtures thereof. Furthermore, we may also use inlieu of, or in admixture with, the alkylene glycols the polyglycolscontaining from 2 to 6 carbon atoms, such as diethylene glycol,triethylene glycol and the like. When mixtures of the various glycolsare employed, the total amount of glycols present equals one mol foreach molar equivalent of phosphorus compound to be reacted. As usedherein and in the appended claims, the term a glycol" is intended tocover mixtures of the various glycols as well as the individual glycolsthemselves.

The saturated aliphatic monohydric alcohol employed contains from 1 to18 carbon atoms.

Various alcohols falling within this class, such as methyl, ethyl,propyl, butyl, 2-ethyl-hexyl, noctyl, dodecyl, cetyl, octadecyl, and thelike are suitable. Particularly good results are obtained with n-octylalcohol. As previously shown, the alcohol is employed in the proportionof 1 mol for each mol of a glycol and each molar equivalent of aphosphorus compound.

In the preparation of our new compounds, a glycol and a saturatedaliphatic monohydric alcohol are mixed together in equimolar proportionsand a molar equivalent of the phosphorus compound is added in successiveportions, with stirring,.at a suitably elevated temperature, say about150 F. After all of the phosphorus compound has been added, thetemperature of the mixture is increased to between about 250 F. and 300F. and maintained at that point until a homogeneous viscous liquid massis obtained. No fixed limits as to the time of reaction need be setforth other than to'state that the reaction should proceed to the pointwhere a substantial increasein viscosity is obtained, but not to such anextent that the reaction mass solidifies upon cooling. Salts of thereaction products obtained within these limits in accordance with ourinvention are excellent foam inhibiting agents. After the reactionbetween the glycol, alcohol and phosphorus compound has proceeded to thedesired point, the residual acidity of the mixture isneutralized by theaddition of a salt-forming compound selected from the class consistingof metal bases and organic ammonium bases selected from the classconsisting of heterocyclic nitrogen bases and N-dialkylarylamines.suitable metal bases are the alkali and alkaline earth metal hydroxides.Suitable heterocyclic nitrogen-bases comprise pyridine, nicotine,furazan and the like. We prefer to form the foam inhibiting salts withthe N-dialkylarylamines, such as dimethylaniline, diethylaniline, etc.

The salts so obtained may then be diluted with inhibiting agent inmineral oil, which may be diluted to the concentrations desired for useunder service conditions. Concentrates'of the salts need not necessarilybe prepared, in which case the foam inhibiting agent may be dissolveddirectly in the mineral oil in the concentration desired for use. Ourmineral oil compositions comprise a major amount of a mineral oil and aminor amount of our new foam inhibiting salt at least sufficient toreduce the foaming tendency of the mineral oil. Generally, a proportionof the foam inhibitor varying from 0.01 to 1.0 per cent by weight on themineral oil is sufllcient to reduce the foaming tendency of the mineraloil.

While we do not desire to be limited by any theory as to the reactionwhich takes place between the glycol, phosphorus compound and thesaturated aliphatic monohydric alcohol in the molar proportions stated.it is our present belief that apolymeric compound is formed. Evidencefor this exists in the facts that (l) the glycol and the phosphoruscompound are each polyfunctional, and (2) during the reaction there is aprogressive increase in the viscosity of the reaction mass.

The following example is typical of the preparation of our new foaminhibiting compounds. As

may be seen from the example, the diethylene glycol and the ethyleneglycol are employed in substantially equimolar amounts, and the molratio of glycols to octyl alcohol to phosphorus oxychloride is 1:1:1.

To a suitable vessel 160 lbs. of diethylene glycol, lbs. of ethyleneglycol and 390* lbs. of octyl alcohol were added and mixed thoroughlyand the temperature brought to 100 F. To this mixture 459 lbs. ofphosphorus oxychloride were added over a period of four hours, duringwhich time the temperature was maintained between F. and 160 F.Thereafter, the temperature of the mixture was increased to 275 F. andmaintained at that point until the mass had substantially increased inviscosity. The temperature was then decreased to F., 5.0 per cent wateradded to Gravity, A. P. I 26.3 Viscosity, SUV:

210 .F 119.9 Flash, C: F. -4-.. 535' Fire, 00: "F 610 Pour, F. 0 Color;NPA 5.5 Carbon residue, per cent 0.54 Neutralization No. 0.05

The above-described lubricatingoil and the same oil with theabove-described addition of 0.04 per cent dimethylaniline salt were eachsubjected to the Gulf No. 1 foam test, the details of which are fullydescribed in our U. 8. Patent No. 2,397,-

I 3'17, March 26, 1946, with the following results:

Base Inhibited oil oil Volume of Oil and Foam Batioof vol not 3 l0 4 4.3I,

The outstanding superiority of our new foam-inhibiting compositions isthusclearly evidenced.

Our foam inhibitors are eife'ctivein many types of oils, bothuncompounded and compounded with other improvement agents. Althoughcompounded oils containing our foam inhibitors are particu- 8 What weclaim is:

1. A mineral oil composition resistant to foaming comprising a majoramount of a mineral oil larly useful for applications where resistanceto foaming'is an important consideration, the compounds described hereinmay impart one or more other desirable properties to mineral lubricatingoil compositions. For example. the compounds described hereinaboveinhibit the corrosion of alloy bearings and at the same time reduce theamount of wear produced as compared with a straight uncompounded mineraloil. Moreover, these compounds have mild detergent properties which areadvantageous for certain types of lubrication. In general, thecompounded mi'neral oils containing the foam inhibiting agents disclosedhave better anti-foam, anti-oxidant, oiliness, pressure carrying andanti-ring sticking properties than-the sametype of imcompounded oils.

and an amount at least suflicient to reduce the.

foaming tendency of said 011 of a salt of (1) a salt-forming constituentselected from the class consisting of metals and an organic ammoniumgroup derived from the class consisting of heterocyclic nitrogen basesand N-dialkarylamines and (2) the viscous liquid reaction product ofheating at a temperature not exceeding 300 F. 1 mol of a glycol havingfrom 2 to 6 carbon atoms, 1 molar equivalent of a phosphorus compoundselected from the class consisting of phosphorus oxychloride andphosphorus pentoxide and 1 mol of a saturated aliphatic monohydricalcohol having from 1 to 18 carbon atoms.

2. The composition of claim 1 wherein the proportion of said salt isbetween 0.01 and 1.0 per cent by weight on the mineral oil.

3. The composition of claim 1 wherein the glycol is a mixture of apolyglycol and an alkylene glycol, each of which contains from 2 to 6carbon atoms.

4. A mineral oil composition resistant to foaming comprising a majoramount of a mineral oil and an amount at least sufiicient to reduce thefoaming tendency of said oil of a salt of an N-dlalkylarylamine and theviscous liquid reaction product of heating at a temperature notexceeding 300 F. 1 mol of a glycol having from 2 to 6 carbon atoms, 1molar equivalent of a phosphorus compound selected from the classconsisting of phosphorus oxychloride and phosphorus pentoxide and 1 molof a saturated aliphatic 'monohydric alcohol having from 1 to 18 carbonatoms.

5. A mineral oil composition resistant to foam- I ing comprising a majoramount of a mineral oil and an amount at least sufficient to reduce thefoaming tendency of said oil ofthe salt of dimethylaniline and theviscous liquid reaction product of heating at a temperature notexceeding 300 F. 1 mol of an equimolar mixture of diethylene glycol andethylene glycol, 1 mol of phosphorus 'oxychloride and 1 mol of octylalcohol.

6. The composition of claim 5 wherein the proportion of said saltsisbetween 0.01 and 1.0 per cent by weight on the mineral oil.

' HERSCHEI. G. SMITH. TROY L. CANTRELL.

Romances crrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,411,871 Smith Nov. 26, 1946

